package com.zzsy.shoppingpro.home.view;

import android.content.Context;
import android.os.Handler;
import android.os.Message;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.widget.RelativeLayout;
import android.widget.ScrollView;

import java.util.Timer;
import java.util.TimerTask;

/**
 * Created by Administrator on 2019/8/27 0027.
 */

public class ScrollViewContainer extends RelativeLayout {

    /**
     * 自动上滑
     * */
    public static final int AUTO_UP = 0;

    /**
     * 自动下滑
     * */
    public static final int AUTO_DOWN = 1;

    /**
     * 动画完成
     * */
    public static final int DONE = 2;

    /**
     * 动画速度
     * */
    public static final float SPEED = 6.5F;

    private boolean isMeasured = false;

    /**
     * 用于计算手滑动的速度
     * */
    private VelocityTracker vt;

    private int mViewHeight;
    private int mViewWidth;

    private View topView;
    private View bottomView;

    private boolean canPullDown;
    private boolean canPullUp;

    private int state = DONE;

    /**
     * 记录当前展示的事哪个view 0是topView 1是bottomViwe
     * */
    private int mCurrentViewIndex = 0;

    /**
     * 手滑动的距离，这个是控制布局的主要变量
     * */
    private float mMoveLen;
    private MyTimer myTimer;
    private float mLastY;

    private Context mContext;
    private int mEvents;

    private Handler handler = new Handler(){
        @Override
        public void handleMessage(Message msg) {
            if (mMoveLen != 0) {
                if (state == AUTO_UP) {
                    mMoveLen -= SPEED;
                    if (mMoveLen <= -mViewHeight) {
                        mMoveLen = -mViewHeight;
                        state = DONE;
                        mCurrentViewIndex = 1;
                    }
                } else if (state == AUTO_DOWN) {
                    mMoveLen += SPEED;
                    if (mMoveLen >= 0) {
                        mMoveLen = 0;
                        state = DONE;
                        mCurrentViewIndex = 0;
                    }
                } else {
                    myTimer.cancel();
                }
            }
            requestLayout();
        }
    };


    public ScrollViewContainer(Context context) {
        super(context);
        this.mContext = context;
        init();
    }

    public ScrollViewContainer(Context context, AttributeSet attrs) {
        super(context, attrs);
        this.mContext = context;
        init();
    }

    public ScrollViewContainer(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        this.mContext = context;
        init();
    }

    private void init() {
        myTimer = new MyTimer(handler);
    }

    @Override
    public boolean dispatchTouchEvent(MotionEvent ev) {
        switch (ev.getActionMasked()) {
        case MotionEvent.ACTION_DOWN:
        if (vt == null)
            vt = VelocityTracker.obtain();
        else
            vt.clear();
        mLastY = ev.getY();
        vt.addMovement(ev);
        mEvents = 0;
        break;
        case MotionEvent.ACTION_POINTER_DOWN:
        case MotionEvent.ACTION_POINTER_UP:
        // 多一只手指按下或抬起时舍弃将要到来的第一个事件move，防止多点拖拽的bug
        mEvents = -1;
        break;
        case MotionEvent.ACTION_MOVE:
        vt.addMovement(ev);
        if (canPullUp && mCurrentViewIndex == 0 && mEvents == 0) {
            mMoveLen += (ev.getY() - mLastY);
            // 防止上下越界
            if (mMoveLen > 0) {
                mMoveLen = 0;
                mCurrentViewIndex = 0;
            } else if (mMoveLen < -mViewHeight) {
                mMoveLen = -mViewHeight;
                mCurrentViewIndex = 1;
            }
            if (mMoveLen < -8) {
                // 防止事件冲突
                ev.setAction(MotionEvent.ACTION_CANCEL);
            }
        } else if (canPullDown && mCurrentViewIndex == 1 && mEvents == 0) {
            mMoveLen += (ev.getY() - mLastY);
            // 防止上下越界
            if (mMoveLen < -mViewHeight) {
                mMoveLen = -mViewHeight;
                mCurrentViewIndex = 1;
            } else if (mMoveLen > 0) {
                mMoveLen = 0;
                mCurrentViewIndex = 0;
            }
            if (mMoveLen > 8 - mViewHeight) {
                // 防止事件冲突
                ev.setAction(MotionEvent.ACTION_CANCEL);
            }
        } else
            mEvents++;
        mLastY = ev.getY();
        requestLayout();
        break;
        case MotionEvent.ACTION_UP:
        mLastY = ev.getY();
        vt.addMovement(ev);
        vt.computeCurrentVelocity(700);
        // 获取Y方向的速度
        float mYV = vt.getYVelocity();
        if (mMoveLen == 0 || mMoveLen == -mViewHeight)
            break;
        if (Math.abs(mYV) < 500) {
            // 速度小于一定值的时候当作静止释放，这时候两个View往哪移动取决于滑动的距离
            if (mMoveLen <= -mViewHeight / 2) {
                state = AUTO_UP;
                //---------------------------------------------------------
            } else if (mMoveLen > -mViewHeight / 2) {
                state = AUTO_DOWN;
            }
        } else {
            // 抬起手指时速度方向决定两个View往哪移动
            if (mYV < 0) {
                state = AUTO_UP;
                //---------------------------------------------------------

            } else {

                state = AUTO_DOWN;

            }
        }
        myTimer.schedule(2);
        try {
            vt.recycle();
            //-------------------------------------------------------
            vt = null;
        } catch (Exception e) {
            e.printStackTrace();
        }
        break;

    }
		super.dispatchTouchEvent(ev);
		return true;
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        topView.layout(0,(int)mMoveLen,mViewWidth,topView.getMeasuredHeight() + (int)mMoveLen);
        bottomView.layout(0,topView.getMeasuredHeight() + (int)mMoveLen,mViewWidth,topView.getMeasuredHeight() +(int)mMoveLen + bottomView.getMeasuredHeight());
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        if(!isMeasured){
            isMeasured = true;

            mViewHeight = getMeasuredHeight();
            mViewWidth = getMeasuredWidth();

            topView = getChildAt(0);
            bottomView = getChildAt(1);

            bottomView.setOnTouchListener(bottomViewTouchListener);
            topView.setOnTouchListener(topViewTouchListener);
        }
    }

    /**
     * 上部触摸事件
     * */
    private OnTouchListener topViewTouchListener = new OnTouchListener() {
        @Override
        public boolean onTouch(View v, MotionEvent event) {
            ScrollView sv = (ScrollView) v;
            if (sv.getScrollY() == (sv.getChildAt(0).getMeasuredHeight() - sv
                    .getMeasuredHeight()) && mCurrentViewIndex == 0)
                canPullUp = true;
            else
                canPullUp = false;
            return false;
        }
    };

    /**
     * 下部触摸事件
     * */
    private OnTouchListener bottomViewTouchListener = new OnTouchListener() {
        @Override
        public boolean onTouch(View v, MotionEvent event) {
            ScrollView sv = (ScrollView) v;
            if (sv.getScrollY() == 0 && mCurrentViewIndex == 1)
                canPullDown = true;
            else
                canPullDown = false;
            return false;
        }
    };

    class MyTimer {
        private Handler handler;
        private Timer timer;
        private MyTask mTask;

        public MyTimer(Handler handler) {
            this.handler = handler;
            timer = new Timer();
        }

        public void schedule(long period) {
            if (mTask != null) {
                mTask.cancel();
                mTask = null;
            }
            mTask = new MyTask(handler);
            timer.schedule(mTask, 0, period);
        }

        public void cancel() {
            if (mTask != null) {
                mTask.cancel();
                mTask = null;
            }
        }

        class MyTask extends TimerTask {
            private Handler handler;

            public MyTask(Handler handler) {
                this.handler = handler;
            }

            @Override
            public void run() {
                handler.obtainMessage().sendToTarget();
            }

        }
    }
}
